In the last twenty years phosphoric acid derivatives have played an important role in plant protection. It appears from the prior art that first place the insecticidal effect of the said components was recognized. The insecticidal and acaricidal effect of phosphoric acid esters was disclosed in Hungarian Patent specifications Nos. 157,085 and 190,843 and also in Hungarian laid-open patent application No. T/34,672. The insecticidal effect of thiophosphoric and -phosphonic acid was described e.g. in Hungarian patent specification No. 188,155 and Hungarian laid-open patent application No. T/37,003, while the insecticidal activity of dithio phosphoric acid derivatives was set forth e.g. in Hungarian patent specifications Nos. 184,742, 186,562 and 186,981.
The fungicidal effect of several phosphine and phosphite derivatives, respectively, was disclosed in Hungarian laid-open patent applications Nos. T/31,985, T/33,356, T/33,374 and T/40,557, while the said activity of phthalimide derivatives was described e.g. in Hungarian patent specification No. 174,708.
In the last five years phosphinate and phosphonate derivatives possessing herbicidal effects have been prepared. Such compounds are disclosed e.g. in Hungarian patent specifications Nos. 184,725, 185,774, 186,422 and 191,363 and also in Hungarian laid-open patent applications Nos. T/31,541, T/33,376 and T/39,335. Hungarian laid-open patent application No. T/39,334 relates to phosphonate derivatives having a plant growth regulating effect.
Phosphoric acid ester derivatives may be of widely varying chemical structure. Several such compounds having insecticidal activity comprise a heterocyclic group. Compounds of this type are disclosed in Hungarian laid-open patent applications Nos. T/39,752, T/39,978, and T/40,448 and further in US patents Nos. 3,317,561 and 3,341,407.
There are further known phosphoric acid ester derivatives in which the phosphorus atom forms part of a 5-7-membered ring comprising three hetero atoms (two oxygen atoms and one phosphorus atom). The said compounds are set forth in US patent specifications No. 3,478,133 and Hungarian laid-open patent application no. T/38,223.
N.I. Zemlianszky and I.V. Muraviev CZhurnal Obshchei Khimii, 34, 1. 89-101, (1964)) on preparing dithiophosphoric acid ester having insecticidal effect and substituted in the B-position of the alkyl radical have found that when the potassium salt of 0,0-di-(.beta.-chloroethyl)-dithio-phosphate is allowed to stand in acetonous solution in a desiccator filled with phosphorous pentoxide, cylization takes place with the precipitation of potassium chloride and a cyclic O,S-ethylene-O-(.beta.-chloroethyl)-thiophosphate is formed. The reaction velocity of the said ring-closure may be inceased by heating the acetonous solution. The authors have not studied further the cyclic compounds and the cited publication has been directed to the preparation of potassium salts of dithiophosphoric acid derivatives and acyl derivatives of dialkyl dithiophosphoric acids.